Oil pressure jumping around

Driving home on the highway tonight, 65-70 mph, my oil pressure gauge started to twitch a little. It would jump to 60, then down to 25 or so, then back up between the 30 and 60, then just below 30. It did it for about a minute, and then just stopped. Oil pressure stayed just around 30 at highway speed after that. I was low on oil and added a quart yesterday... is it possible I put a little too much in? The dipstick is right at full after it's sat for a few hours. It's old, too. 1990 that just rolled 187,000.

Anything I should worry about?

Could be the sensor going bad. How low on oil were you and for how long do you think? Any weird knocking noises going on? I just hit 186,400 on the way back from an Event out in Big Bend and I think still getting 50-60 psi at highway speeds and I think I see 20-30ish at idle around town. I'll have to pay more attention to it next time I'm out and about in the car. I usually just glance and make sure it's pointing in the right direction when I'm driving lol.

Let me bust out my service manual and see what it has for the oil pressure spec.

Edit- Found it.

Quote:

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Oil Pressure

With engine at operating temperature, oil pressure should be 28-43psi at 1000 rpm, and 43-57psi at 3000 rpm.

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It was right at the 0.8L mark for a day or two, probably. I'll look again and see what I'm getting at idle and cruising. Thanks for the info.

Ok so when it's just gotten warmed up, the pressure stays good, just at 30 at idle and up around 50 at 3000. Once it's run for about 10 minutes though, then it's just past the 30 line at 3500 rpm going down the highway. The needle is just about straight up. I'm running Valvoline 10W-30 in it. Should I run 30W in hot weather? (just a curious side note).

I'm guessing that the 22-year-old sensor and gauge are probably not 100% accurate, and the engine doesn't make any funny noises like it's low on oil pressure so I'm not going to worry too much.

Any other info is always greatly appreciated.

So now that I've paid closer attention to it, the pressure stays pretty close all the way from 2000 rpm to 4500 or so. Starts to climb a little above 4500. I'm still going with old sensor/gauge and not that accurate to begin with.

Any good suggestions for a water/oil/volt trio install that's quick, easy, and accurate?